Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile needs no restatement. The description does add useful payload context ('full check-in history'), but says nothing about pagination limits, ordering of check-ins, or behavior when the ID isn't found — gaps that matter given no output schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single well-formed sentence that front-loads the verb and resource and wastes no words. Slightly compact for the amount of unexplained behavior underneath, but structurally clean.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description correctly sketches the return (the key result plus its check-in history), which is the single most important thing an agent needs. However, it omits how checkInLimit bounds that history and what happens on a missing ID, so a calling agent can't fully predict the response.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description carries the full burden, yet it never mentions keyResultId or checkInLimit. The phrase 'full check-in history' actually sits in tension with the checkInLimit default of 10, leaving the agent unaware that history may be truncated.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb ('Get') and resource ('one key result') and adds scope ('with its full check-in history'), which implicitly separates it from the plural list_key_results. It stops short of explicitly contrasting with siblings, but an agent can distinguish it from list_key_results without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The trailing clause 'so you can see how the metric has moved over time' implies the intended use case (trend inspection) but gives no explicit when-to-use criteria, prerequisites, or named alternatives aside from the implicit singular/plural distinction. Adequate but leaves the agent to infer routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.